Re: [Tm-rid] HHIT trust proof for Auth messages

["Wiethuechter, Adam" <[e-mail]>]

All,

Attached is a mock up of what Bob has here just in the new 0.8 version of
the authentication message.

There is a 23 byte payload limit or 25 bytes if we remove the reserved
bytes and condense. I am unwilling to do this though as then the HHIT or
Trust Timestamp fields would be fragmented across pages. Its already bad
enough that the Trusted Timestamp and standard Timestamp fragment across
the 32 bit boundary (within a page) and worse the signature across 3 whole
pages already. While in practice this probably wouldn't affect much it
makes it harder to understand/read I think.

My concern, is that we are broadcasting over Bluetooth. There are 5 pages
to the authentication message (from my understanding of the new standard).
If we lose any one page it is most likely going to be a signature page (as
it spans 3 whole pages) and there will be no way to achieve that which this
format is intended for without the full signature. Perhaps the payload
section that Bob marked in (and fills the final page of the authentication
message) should be some sort of error correction on the signature?

The second version I think is unattainable in the new format, unless
someone here can defy the laws of physics and make numbers smaller than
they actually are thus allowing more to fit within the 109 byte constrain
of the message format.

Questions, comments, concerns?

On Fri, Sep 27, 2019 at 12:40 PM Robert Moskowitz <[e-mail]>
wrote:

> And here is something I have been working on as condensed proof of HHIT
> ownership objects that can be put into the auth messages.  I have not
> done that yet, like Adam has:
>
>      <figure>
>          <artwork>
>     0                   1 2                   3
>     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> |                                                               |
>    | HHIT                              |
> |                                                               |
> |                                                               |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>    | TIMESTAMP                          |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> |                                                               |
>    | HHIT                              |
>    | SIG                              |
> .                                                               .
> .                                                               .
> .                                                               .
> |                                                               |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>    / PAYLOAD                            /
> /                                                               /
>    / +-------------------------------+
>    / |                               |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
>    HHIT           16 byte HHIT of EdDSA25519 HI
>    TIMESTAMP      4 byte packet trust until timestamp
>    HHIT SIG       64 byte Signature of whole packet
>    PAYLOAD        0 to n bytes of payload
>        Length     84 + n bytes
>          </artwork>
>      </figure>
>      <figure>
>          <artwork>
>     0                   1 2                   3
>     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> |                                                               |
>    |                            DEV HHIT                           |
> |                                                               |
> |                                                               |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>    | TIMESTAMP                          |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> |                                                               |
>    |                            DEV HHIT                           |
>    | SIG                              |
> .                                                               .
> .                                                               .
> .                                                               .
> |                                                               |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> |                                                               |
>    |                              DEV HI                           |
> |                                                               |
> |                                                               |
> |                                                               |
> |                                                               |
> |                                                               |
> |                                                               |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>    |                         AUTH TIMESTAMP                        |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> |                                                               |
>    |                           AUTH HHIT                           |
> |                                                               |
> |                                                               |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> |                                                               |
>    | AUTH                               |
>    | SIG                              |
> .                                                               .
> .                                                               .
> .                                                               .
> |                                                               |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>    / PAYLOAD                            /
> /                                                               /
>    / +-------------------------------+
>    / |                               |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>
>    DEV HHIT       16 byte Dev HHIT of EdDSA25519 HI
>    TIMESTAMP      4 byte packet trust until timestamp
>    DEV HHIT SIG   64 byte Signature of whole packet
>    DEV HI         32 byte Device HI of EdDSA25519 HI
>    AUTH TIMESTAMP 4 byte Dev HHIT trust until timestamp
>    AUTH HHIT      16 byte Authorizer's HHIT of EdDSA25519 HI
>    AUTH SIG       64 byte Signature of Device HHIT-HI
>    PAYLOAD        0 to n bytes of payload
>        Length    200 + n bytes
>          </artwork>
>      </figure>
>
>    |             Type              | Length            |
>
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-- 
73's,
Adam T. Wiethuechter